Urinary incontinence is a widespread problem throughout the world. Urinary incontinence affects people of all ages and can severely impact a patient both physiologically and psychologically.
One form of urinary incontinence suffered by women is intrinsic sphincter deficiency (ISD), a condition in which the valve of the urethral sphincter does not function properly, thus preventing proper coaptation of the urethra. Without proper coaptation, a person is unable to control urinary leakage. ISD can arise from loss of urethral vasculature, thinning of urethral mucosa, loss of the urethral connective tissue elements, neurologic compromise of the sympathetic smooth muscle, or compromise of the external striated sphincter.
Another form of urinary incontinence is known as bladder neck hypermobility. Bladder neck hypermobility can arise from loss of support by the pelvic floor and loss of suspension by the pelvic connective tissue in ligaments and fascia. In this condition, the bladder neck and proximal urethra descend in response to increases in intra-abdominal pressure, resulting in uncontrollable urinary leakage.
Common approaches to treating urinary incontinence in women require invasive surgical procedures either through the vaginal wall or the abdominal wall. These surgical procedures focus on elevating the urethrovesical junction by introducing a sling that passes to the posterior side of the urethra and suspending the urethra from an anatomical structure located anterior to the urethra, for example, the abdominal fascia, the pubic bone, or the Cooper's ligament. Surgical treatments of urinary incontinence that use slings typically involve placing the sling under the urethra to provide suburethral support. Slings of this type simultaneously compress and suspend the urethra to treat urinary incontinence. One disadvantage of these procedures is the invasive nature of these procedures. Another disadvantage is that weight gain or loss can affect the suspension of the urethra causing it to become too tight or too loose. Still another disadvantage is that some types of slings may shrink with age and may cause difficulties with voiding. Other invasive surgical approaches to treating urinary incontinence include the use of vaginal wall slings and/or artificial urinary sphincters.
Periurethral injection (PI) of biocompatible bulk-enhancing agents, another approach to treating urinary incontinence, has the advantage of being a less invasive form of treatment and, thus, can be performed on an outpatient basis. PI uses bulk-enhancing agents, such as, Teflon® (DuPont), autologous fat, and collagen, to increase pressure on the urethra and reduce the size of the urethral lumen, providing additional resistance to the flow of urine. Such injections may be accomplished either transurethrally or periurethrally. Typically, however, repeat treatments of PI are required because the bulk-enhancing agent can be absorbed by the body or translocated from the site of injection. Another drawback to PI is that accidental over-bulking may result in undesirable urinary retention requiring catheterization to void until the injectant is absorbed by the body.